This study is multicentered and will investigate the use of intracoronary ultrasound in transplant patients post heart transplant while the patients undergo annual angiographic evaluation to look for coronary artery disease. Correlation of assessment of graft arteriography by intracoronary ultrasound vs. quantitative angiography, determination of effectiveness of intracoronary ultrasound and evaluation of natural graft arteriopathy history will be done.